Re: Pole Pig Construction

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "tesla by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla-at-paradise-dot-net.nz>

Hi Ken
Most intertesting points you make re floating the cores of MOT's in stacked
operation.
Some observations on your comments

1) Yes it will distribute the stress between elements as you say.
2) Is this a good idea ? I have my doubts here. The primary is not made to
accept this stress whereas the secondary is particularly near the outer part
which must hold back 2.2kv or so.
3) I think in all likelyhood MOT's are tough enough for either
configuration.
4) There is an element of safety I think in gnd the core operation. It is
not possible for secondary voltages to reach back to the mains I/P with the
associated risks of that event. It also places a barrier between the mains
and any secondary strikes.
5) As you say simple series operation MUST introduce core to secondary
stress. The distribution of this stress can be managed by adopting various
configurations BUT it works OK in practice. MOT coilers report success
regularly. I don't know what the limit is but 4 per side in oil is reported
without failures.
6) I do not have heat problems in my MOT's BUT I am sure that submersion in
oil will assist in heat removal. The thermal contact and conduction of oil
is >> than air.
Some posters have said it is essential even for the unmodified MOT's in the
centre for this reason. I guess it all depends on the amount of ballasting
and length of run times. I use modest ballasting to keep from overloading my
MOT's.

7) The impact of oil use may just be a personal thing. Don't Pigs have oil
in them too. It can be managed easily with good construction. For me it has
been a set it (and yes putting the oil in was a little messy) and forget it
thing.

8) MOT use is commented  by me in  to help those looking for cheap and easy
to get bits. I'm not trying to dismiss the pig at all I just respond to MOT
"put downs" which I feel are unbalanced . Many potential users rely on the
"flavour" they get from postings. Most can't afford or are not equipped to
use PIG's and I try to offer balancing thoughts and offer tips for those who
might be thinking of using MOT's

9) Yes a 200lb PIG can be moved as you say but 6x10 is OK too.

It's odd to me that there is a pro/anti MOT vs other options it's just a
horses for courses thing. BTW I'm not suggesting your post was in any
particular camp on this point.

Best to all
Ted L in NZ